Solid oxide fuel cells are a type of fuel cell where oxygen ions pass through an electrolyte membrane. For these types of fuel cells, the electrolyte membrane is usually a solid ceramic. The ion conducting properties of prior art membranes usually does not begin until fairly high temperatures, on the order of 800° C. This document describes the fabrication of highly efficient solid oxide fuel cells with a thin film electrolyte and electrode structure.
A solid oxide fuel cell can be manufactured using standard photo lithographic techniques. These techniques allow for fairly precise construction. Given the availability and precision of the equipment, a solid oxide fuel cell with a thin layer electrolyte membrane can be constructed. Depending on the material of the membrane, the ion conductivity of the membrane goes up as the thickness of the membrane goes down. Unfortunately, with prior art very thin film membranes, the structural integrity of the solid oxide fuel cell can be compromised.
By using a Yttria Stabilized Zirconia (YSZ) or a Gadolinia-Doped Ceria (GDC), a thin film membrane on the order of 50 nm can be manufactured and operated successfully. The GDC membrane fuel cell can operate around 300° C., which is a very low operating temperature for a solid oxide fuel cell. The YSZ membrane fuel cell has a higher operating temperature, but can offer better ion conductivity than the GDC fuel cell at the same temperature.